The present invention relates to picture elements of a color liquid-crystal display apparatus, color arrangements of coloring means, and electric control.
The color liquid-crystal display apparatus is provided with many picture elements arranged in dot-matrix shape and a coloring means arranged corresponding to each picture element. Each picture element is controlled through application of a picture signal corresponding to a color corresponding to each picture element so that colors are additively mixed in accordance with the same principle as that of a color CRT, with the result that an arbitrary color picture including a half tone color image may be displayed. Read "Liquid-Crystal Electronics Base And Application" (Ohm Company, 1979) or the like edited by Sasaki for details on the liquid crystal.
Many modes such as twisted-nematic (TN), guest-host (GH), dynamic-scattering-mode (DSM), phase transfer, etc. are available as an operation mode of a liquid crystal display apparatus. Particularly the TN and GH modes provide favorable results. In the guest-host, black die is used and is operated as a so-called black shutter.
Normally additive three primary colors are selected as the colors of the coloring means. An interference filter, a color filter made of inorganic or organic dye or pigment are used in the coloring means. The coloring means may be provided on the outer face of a substrate which constitutes a liquid crystal display apparatus or on the inner face thereoi. In the case of the latter, the coloring means may be provided on or below a signal electrode, a scanning electrode, a picture element electrode or a common electrode.
In the color liquid crystal display apparatus, only the spectrum region of one color of three primary colors among the spectra of the incident light can be used and the remaining regions are absorbed by the coloring means. In the case of a liquid crystal operation mode using a polarizer, the light intensity to be used is further reduced by half so that it is very dark in a reflection type mode with no illuminating means in it. Thus, a light source such an incandescent lamp, fluorescent lamp, EL (Electro-luminescence) panel or the like is provided or a means for guiding ambient light to the rear face of the liquid crystal display apparatus are provided as the illuminating means. For application to a portable appliance, it is important to improve the radiation efficiency of the light source because of the severe restriction in power capacity. To faithfully reproduce picture signals, many picture elements, i.e., many scanning lines are required. For example, a liquid crystal panel for color television use will be considered. In the NTSC system of television broadcasting, the band width of the luminance signal (Y signal) is 4 MHz, while the band widths of I signal and Q signal which are color phase signals are respectively 1.5 MHz, 5.0 MHz As the sine waves of the 0.5 MHz includes 26.5 cycle waves in the 1 effective horizontal scanning period (53 microseconds), the horizontal resolution is equivalent to 53 lines or 26.5 line pairs of bright lines and dark lines. According to the theorem of Shannon, the loss of the information contained in the original signal cannot be caused if the sampling operation is performed with a frequency twice the highest frequency of the original signal. However, it is difficult to say that the images provided when the signals sampled in that manner have been reproduced as they are are visually faithful to the original signal under the influences of aliasing. As the result of our experiment visual satisfaction is provided when the sampling has been performed with a frequency higher than three times the highest frequency. Accordingly, to reproduce the color signal of 0.5 MHz, the information having the original signal can be reproduced almost faithfully if the number of the picture elements of the same color on the same horizontal line is 80 and more.
In a liquid crystal display apparatus provided with many picture elements, one of the following three methods is used to individually control the respective picture elements.